1. Field of the Invention
This invention concerns the condensation of 1,4-dihydroxybenzenes to form the corresponding 4,4'-dihydroxydiphenyl ethers.
2. Description of the Prior Art
It is known from German Specification No. 2,237,762 to prepare 4,4'-dihydroxdiphenyl ether by condensing 1,4-dihydroxybenzene in the presence of free acid-containing aluminum silicate catalyst. of similar import is British Pat. No. 1,031,486. U.S. Pat. No. 2,739,171 concerns preparation of dihydroxy diaryl ethers in the presence of a catalyst selected from hydrofluoric and phosphoric acids, alumina, silica, zirconia and magnesia. U.S. Pat. No. 3,037,052 discloses the cation exchange resins employed in the process of this invention. Said resins are disclosed, however, for the esterification of alkyl starting reactants.
The 4,4'-dihydroxydiphenyl ethers made by the process of this invention can be reacted with dibasic carboxylic acids according to known technology to prepare polyester fibers and resins. In addition, plasticizers and antioxidants can be made by esterification or ring alkylation of the product ethers.